Methods for MAC frame extensibility and frame specific MAC header design for WLAN systems

ABSTRACT

A method and apparatus are provided for processing a Class-3 MAC Data frame. The Class-3 MAC Data frame may include a Type field, a Subtype field, and a Class-3 MAC Data frame-specific MAC subheader that includes a basic service set identifier (BSSID) field, an association identifier (AID) field, and a direction indicator. A station (STA) may determine the intended recipient of the Class-3 MAC Data frame based on the BSSID field, the AID field, and the direction indicator.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application No.61/697,126 filed Sep. 5, 2012, the contents of which are herebyincorporated by reference herein.

BACKGROUND

An IEEE 802.11-based Wireless Local Area Network (WLAN) system providespacket based data communications among Stations (STAs) over a wirelessmedium. At the Medium Access Control (MAC) sublayer, the MAC ServiceData Units (MSDUs) are received from or delivered to the upper layer;and MAC Protocol Data Units (MPDUs) are formed and transported betweenMAC peer STAs. MPDUs are also called MAC frames in the IEEE 802.11standard.

A MAC frame type is identified by a combination of a 2-bit Type fieldand a 4-byte Subtype field in the Frame Control field of the MAC header.There are three frame types defined in the IEEE 802.11-2012specification, including the Management frame, the Control frame, andthe Data frame. For each frame type, multiple Subtypes have beendefined, as shown in Table 8-1 in the IEEE 802.11-2012 specification. Inthe IEEE 802.11ad draft standard, another frame type is defined, calledan Extension frame. Two Subtype values have been defined for theExtension frame type, a directional multi-gigabit (DMG) Beacon subtypeand a short beacon frame subtype.

A MAC frame generally consists of three basic components: A MAC header,which comprises a frame control field, a duration field, an addressfield, optional sequence control information, optional quality ofservice (QoS) Control information (QoS data frames only), and optionalHT Control fields (+HTC frames only); a variable-length frame body,which contains information specific to the frame type and subtype; and aframe check sequence (FCS), which contains an IEEE 32-bit cyclicredundancy check (CRC).

SUMMARY

A method and apparatus are provided for processing a Class-3 MAC Dataframe. The Class-3 MAC Data frame may include a Type field, a Subtypefield, and a Class-3 MAC Data frame-specific MAC subheader that includesa basic service set identifier (BSSID) field, an association identifier(AID) field, and a direction indicator. A station (STA) may determinethe intended recipient of the Class-3 MAC Data frame based on the BSSIDfield, the AID field, and the direction indicator.

BRIEF DESCRIPTION OF THE DRAWINGS

A more detailed understanding may be had from the following description,given by way of example in conjunction with the accompanying drawingswherein:

FIG. 1A is a system diagram of an example communications system in whichone or more disclosed embodiments may be implemented;

FIG. 1B is a system diagram of an example wireless transmit/receive unit(WTRU) that may be used within the communications system illustrated inFIG. 1A;

FIG. 1C is a system diagram of an example radio access network and anexample core network that may be used within the communications systemillustrated in FIG. 1A;

FIG. 2 shows the IEEE 802.11 MAC Management frame format;

FIG. 3 illustrates an example IEEE 802.11 MAC Extension-2 frame format;

FIG. 4 shows a flow diagram for a possible Extension-2 frame processingprocedure;

FIG. 5 depicts example IEEE 802.11 MAC Frame Type Specific Extension-2frame formats using a general Extension-2 Frame Type;

FIG. 6 shows example IEEE 802.11 MAC Frame Type Specific Extension-2frame formats using a Management Frame Type, a Control Frame Type, and aData Frame Type;

FIG. 7 shows a possible basic MAC frame format with an inventive MACheader;

FIG. 8 depicts a possible basic structure of a Frame-Specific MACsubheader;

FIG. 9 illustrates an Infrastructure BSS Beacon frame with an inventiveMAC header design;

FIG. 10 shows a Fast Initial Link Setup (FILS) Discovery Frame with aninventive MAC header design;

FIG. 11 illustrates a Class-3 MAC Data frame with an inventive MACheader design;

FIG. 12 shows a flow diagram for a possible Class-3 MAC Data frameprocessing procedure;

FIG. 13 shows a flow diagram for a possible Multicast Class-3 MAC Dataframe processing procedure; and

FIG. 14 shown an example Extended Information Element (EIE) format.

DETAILED DESCRIPTION

FIG. 1A is a diagram of an example communications system 100 in whichone or more disclosed embodiments may be implemented. The communicationssystem 100 may be a multiple access system that provides content, suchas voice, data, video, messaging, broadcast, etc., to multiple wirelessusers. The communications system 100 may enable multiple wireless usersto access such content through the sharing of system resources,including wireless bandwidth. For example, the communications systems100 may employ one or more channel access methods, such as code divisionmultiple access (CDMA), time division multiple access (TDMA), frequencydivision multiple access (FDMA), orthogonal FDMA (OFDMA), single-carrierFDMA (SC-FDMA), and the like.

As shown in FIG. 1A, the communications system 100 may include wirelesstransmit/receive units (WTRUs) 102 a, 102 b, 102 c, 102 d, a radioaccess network (RAN) 104, a core network 106, a public switchedtelephone network (PSTN) 108, the Internet 110, and other networks 112,though it will be appreciated that the disclosed embodiments contemplateany number of WTRUs, base stations, networks, and/or network elements.Each of the WTRUs 102 a, 102 b, 102 c, 102 d may be any type of deviceconfigured to operate and/or communicate in a wireless environment. Byway of example, the WTRUs 102 a, 102 b, 102 c, 102 d may be configuredto transmit and/or receive wireless signals and may include userequipment (UE), a station (STA), a mobile station, a fixed or mobilesubscriber unit, a pager, a cellular telephone, a personal digitalassistant (PDA), a smartphone, a laptop, a netbook, a personal computer,a wireless sensor, consumer electronics, and the like.

The communications systems 100 may also include a base station 114 a anda base station 114 b. Each of the base stations 114 a, 114 b may be anytype of device configured to wirelessly interface with at least one ofthe WTRUs 102 a, 102 b, 102 c, 102 d to facilitate access to one or morecommunication networks, such as the core network 106, the Internet 110,and/or the other networks 112. By way of example, the base stations 114a, 114 b may be a base transceiver station (BTS), a Node-B, an eNode B,a Home Node B, a Home eNode B, a site controller, an access point (AP),a wireless router, a station (STA), and the like. While the basestations 114 a, 114 b are each depicted as a single element, it will beappreciated that the base stations 114 a, 114 b may include any numberof interconnected base stations and/or network elements.

The base station 114 a may be part of the RAN 104, which may alsoinclude other base stations and/or network elements (not shown), such asa base station controller (BSC), a radio network controller (RNC), relaynodes, etc. The base station 114 a and/or the base station 114 b may beconfigured to transmit and/or receive wireless signals within aparticular geographic region, which may be referred to as a cell (notshown). The cell may further be divided into cell sectors. For example,the cell associated with the base station 114 a may be divided intothree sectors. Thus, in one embodiment, the base station 114 a mayinclude three transceivers, i.e., one for each sector of the cell. Inanother embodiment, the base station 114 a may employ multiple-inputmultiple-output (MIMO) technology and, therefore, may utilize multipletransceivers for each sector of the cell.

The base stations 114 a, 114 b may communicate with one or more of theWTRUs 102 a, 102 b, 102 c, 102 d over an air interface 116, which may beany suitable wireless communication link (e.g., radio frequency (RF),microwave, infrared (IR), ultraviolet (UV), visible light, etc.). Theair interface 116 may be established using any suitable radio accesstechnology (RAT).

More specifically, as noted above, the communications system 100 may bea multiple access system and may employ one or more channel accessschemes, such as CDMA, TDMA, FDMA, OFDMA, SC-FDMA, and the like. Forexample, the base station 114 a in the RAN 104 and the WTRUs 102 a, 102b, 102 c may implement a radio technology such as Universal MobileTelecommunications System (UMTS) Terrestrial Radio Access (UTRA), whichmay establish the air interface 116 using wideband CDMA (WCDMA). WCDMAmay include communication protocols such as High-Speed Packet Access(HSPA) and/or Evolved HSPA (HSPA+). HSPA may include High-Speed DownlinkPacket Access (HSDPA) and/or High-Speed Uplink Packet Access (HSUPA).

In another embodiment, the base station 114 a and the WTRUs 102 a, 102b, 102 c may implement a radio technology such as Evolved UMTSTerrestrial Radio Access (E-UTRA), which may establish the air interface116 using Long Term Evolution (LTE) and/or LTE-Advanced (LTE-A).

In other embodiments, the base station 114 a and the WTRUs 102 a, 102 b,102 c may implement radio technologies such as IEEE 802.16 (i.e.,Worldwide Interoperability for Microwave Access (WiMAX)), CDMA2000,CDMA2000 1×, CDMA2000 EV-DO, Interim Standard 2000 (IS-2000), InterimStandard 95 (IS-95), Interim Standard 856 (IS-856), Global System forMobile communications (GSM), Enhanced Data rates for GSM Evolution(EDGE), GSM EDGE (GERAN), and the like.

The base station 114 b in FIG. 1A may be a wireless router, Home Node B,Home eNode B, or access point, for example, and may utilize any suitableRAT for facilitating wireless connectivity in a localized area, such asa place of business, a home, a vehicle, a campus, and the like. In oneembodiment, the base station 114 b and the WTRUs 102 c, 102 d mayimplement a radio technology such as IEEE 802.11 to establish a wirelesslocal area network (WLAN). In another embodiment, the base station 114 band the WTRUs 102 c, 102 d may implement a radio technology such as IEEE802.15 to establish a wireless personal area network (WPAN). In yetanother embodiment, the base station 114 b and the WTRUs 102 c, 102 dmay utilize a cellular-based RAT (e.g., WCDMA, CDMA2000, GSM, LTE,LTE-A, etc.) to establish a picocell or femtocell. As shown in FIG. 1A,the base station 114 b may have a direct connection to the Internet 110.Thus, the base station 114 b may not be required to access the Internet110 via the core network 106.

The RAN 104 may be in communication with the core network 106, which maybe any type of network configured to provide voice, data, applications,and/or voice over internet protocol (VoIP) services to one or more ofthe WTRUs 102 a, 102 b, 102 c, 102 d. For example, the core network 106may provide call control, billing services, mobile location-basedservices, pre-paid calling, Internet connectivity, video distribution,etc., and/or perform high-level security functions, such as userauthentication. Although not shown in FIG. 1A, it will be appreciatedthat the RAN 104 and/or the core network 106 may be in direct orindirect communication with other RANs that employ the same RAT as theRAN 104 or a different RAT. For example, in addition to being connectedto the RAN 104, which may be utilizing an E-UTRA radio technology, thecore network 106 may also be in communication with another RAN (notshown) employing a GSM radio technology.

The core network 106 may also serve as a gateway for the WTRUs 102 a,102 b, 102 c, 102 d to access the PSTN 108, the Internet 110, and/orother networks 112. The PSTN 108 may include circuit-switched telephonenetworks that provide plain old telephone service (POTS). The Internet110 may include a global system of interconnected computer networks anddevices that use common communication protocols, such as thetransmission control protocol (TCP), user datagram protocol (UDP) andthe internet protocol (IP) in the TCP/IP internet protocol suite. Thenetworks 112 may include wired or wireless communications networks ownedand/or operated by other service providers. For example, the networks112 may include another core network connected to one or more RANs,which may employ the same RAT as the RAN 104 or a different RAT.

Some or all of the WTRUs 102 a, 102 b, 102 c, 102 d in thecommunications system 100 may include multi-mode capabilities, i.e., theWTRUs 102 a, 102 b, 102 c, 102 d may include multiple transceivers forcommunicating with different wireless networks over different wirelesslinks. For example, the WTRU 102 c shown in FIG. 1A may be configured tocommunicate with the base station 114 a, which may employ acellular-based radio technology, and with the base station 114 b, whichmay employ an IEEE 802 radio technology.

FIG. 1B is a system diagram of an example WTRU 102. As shown in FIG. 1B,the WTRU 102 may include a processor 118, a transceiver 120, atransmit/receive element 122, a speaker/microphone 124, a keypad 126, adisplay/touchpad 128, non-removable memory 130, removable memory 132, apower source 134, a global positioning system (GPS) chipset 136, andother peripherals 138. It will be appreciated that the WTRU 102 mayinclude any sub-combination of the foregoing elements while remainingconsistent with an embodiment.

The processor 118 may be a general purpose processor, a special purposeprocessor, a conventional processor, a digital signal processor (DSP), aplurality of microprocessors, one or more microprocessors in associationwith a DSP core, a controller, a microcontroller, Application SpecificIntegrated Circuits (ASICs), Field Programmable Gate Array (FPGAs)circuits, any other type of integrated circuit (IC), a state machine,and the like. The processor 118 may perform signal coding, dataprocessing, power control, input/output processing, and/or any otherfunctionality that enables the WTRU 102 to operate in a wirelessenvironment. The processor 118 may be coupled to the transceiver 120,which may be coupled to the transmit/receive element 122. While FIG. 1Bdepicts the processor 118 and the transceiver 120 as separatecomponents, it will be appreciated that the processor 118 and thetransceiver 120 may be integrated together in an electronic package orchip.

The transmit/receive element 122 may be configured to transmit signalsto, or receive signals from, a base station (e.g., the base station 114a) over the air interface 116. For example, in one embodiment, thetransmit/receive element 122 may be an antenna configured to transmitand/or receive RF signals. In another embodiment, the transmit/receiveelement 122 may be an emitter/detector configured to transmit and/orreceive IR, UV, or visible light signals, for example. In yet anotherembodiment, the transmit/receive element 122 may be configured totransmit and receive both RF and light signals. It will be appreciatedthat the transmit/receive element 122 may be configured to transmitand/or receive any combination of wireless signals.

In addition, although the transmit/receive element 122 is depicted inFIG. 1B as a single element, the WTRU 102 may include any number oftransmit/receive elements 122. More specifically, the WTRU 102 mayemploy MIMO technology. Thus, in one embodiment, the WTRU 102 mayinclude two or more transmit/receive elements 122 (e.g., multipleantennas) for transmitting and receiving wireless signals over the airinterface 116.

The transceiver 120 may be configured to modulate the signals that areto be transmitted by the transmit/receive element 122 and to demodulatethe signals that are received by the transmit/receive element 122. Asnoted above, the WTRU 102 may have multi-mode capabilities. Thus, thetransceiver 120 may include multiple transceivers for enabling the WTRU102 to communicate via multiple RATs, such as UTRA and IEEE 802.11, forexample.

The processor 118 of the WTRU 102 may be coupled to, and may receiveuser input data from, the speaker/microphone 124, the keypad 126, and/orthe display/touchpad 128 (e.g., a liquid crystal display (LCD) displayunit or organic light-emitting diode (OLED) display unit). The processor118 may also output user data to the speaker/microphone 124, the keypad126, and/or the display/touchpad 128. In addition, the processor 118 mayaccess information from, and store data in, any type of suitable memory,such as the non-removable memory 130 and/or the removable memory 132.The non-removable memory 130 may include random-access memory (RAM),read-only memory (ROM), a hard disk, or any other type of memory storagedevice. The removable memory 132 may include a subscriber identitymodule (SIM) card, a memory stick, a secure digital (SD) memory card,and the like. In other embodiments, the processor 118 may accessinformation from, and store data in, memory that is not physicallylocated on the WTRU 102, such as on a server or a home computer (notshown).

The processor 118 may receive power from the power source 134, and maybe configured to distribute and/or control the power to the othercomponents in the WTRU 102. The power source 134 may be any suitabledevice for powering the WTRU 102. For example, the power source 134 mayinclude one or more dry cell batteries (e.g., nickel-cadmium (NiCd),nickel-zinc (NiZn), nickel metal hydride (NiMH), lithium-ion (Li-ion),etc.), solar cells, fuel cells, and the like.

The processor 118 may also be coupled to the GPS chipset 136, which maybe configured to provide location information (e.g., longitude andlatitude) regarding the current location of the WTRU 102. In additionto, or in lieu of, the information from the GPS chipset 136, the WTRU102 may receive location information over the air interface 116 from abase station (e.g., base stations 114 a, 114 b) and/or determine itslocation based on the timing of the signals being received from two ormore nearby base stations. It will be appreciated that the WTRU 102 mayacquire location information by way of any suitablelocation-determination method while remaining consistent with anembodiment.

The processor 118 may further be coupled to other peripherals 138, whichmay include one or more software and/or hardware modules that provideadditional features, functionality and/or wired or wirelessconnectivity. For example, the peripherals 138 may include anaccelerometer, an e-compass, a satellite transceiver, a digital camera(for photographs or video), a universal serial bus (USB) port, avibration device, a television transceiver, a hands free headset, aBluetooth® module, a frequency modulated (FM) radio unit, a digitalmusic player, a media player, a video game player module, an Internetbrowser, and the like.

As shown in FIG. 1C, the RAN 104 may include base stations 140 a, 140 b,140 c, and an ASN gateway 142, though it will be appreciated that theRAN 104 may include any number of base stations and ASN gateways whileremaining consistent with an embodiment. The base stations 140 a, 140 b,140 c may each be associated with a particular cell (not shown) in theRAN 104 and may each include one or more transceivers for communicatingwith the WTRUs 102 a, 102 b, 102 c over the air interface 116. In oneembodiment, the base stations 140 a, 140 b, 140 c may implement MIMOtechnology. Thus, the base station 140 a, for example, may use multipleantennas to transmit wireless signals to, and receive wireless signalsfrom, the WTRU 102 a. The base stations 140 a, 140 b, 140 c may alsoprovide mobility management functions, such as handoff triggering,tunnel establishment, radio resource management, traffic classification,quality of service (QoS) policy enforcement, and the like. The ASNgateway 142 may serve as a traffic aggregation point and may beresponsible for paging, caching of subscriber profiles, routing to thecore network 106, and the like.

The air interface 116 between the WTRUs 102 a, 102 b, 102 c and the RAN104 may be defined as an R1 reference point that implements the IEEE802.16 specification. In addition, each of the WTRUs 102 a, 102 b, 102 cmay establish a logical interface (not shown) with the core network 106.The logical interface between the WTRUs 102 a, 102 b, 102 c and the corenetwork 106 may be defined as an R2 reference point, which may be usedfor authentication, authorization, IP host configuration management,and/or mobility management.

The communication link between each of the base stations 140 a, 140 b,140 c may be defined as an R8 reference point that includes protocolsfor facilitating WTRU handovers and the transfer of data between basestations. The communication link between the base stations 140 a, 140 b,140 c and the ASN gateway 215 may be defined as an R6 reference point.The R6 reference point may include protocols for facilitating mobilitymanagement based on mobility events associated with each of the WTRUs102 a, 102 b, 100 c.

As shown in FIG. 1C, the RAN 104 may be connected to the core network106. The communication link between the RAN 104 and the core network 106may defined as an R3 reference point that includes protocols forfacilitating data transfer and mobility management capabilities, forexample. The core network 106 may include a mobile IP home agent(MIP-HA) 144, an authentication, authorization, accounting (AAA) server146, and a gateway 148. While each of the foregoing elements aredepicted as part of the core network 106, it will be appreciated thatany one of these elements may be owned and/or operated by an entityother than the core network operator.

The MIP-HA may be responsible for IP address management, and may enablethe WTRUs 102 a, 102 b, 102 c to roam between different ASNs and/ordifferent core networks. The MIP-HA 144 may provide the WTRUs 102 a, 102b, 102 c with access to packet-switched networks, such as the Internet110, to facilitate communications between the WTRUs 102 a, 102 b, 102 cand IP-enabled devices. The AAA server 146 may be responsible for userauthentication and for supporting user services. The gateway 148 mayfacilitate interworking with other networks. For example, the gateway148 may provide the WTRUs 102 a, 102 b, 102 c with access tocircuit-switched networks, such as the PSTN 108, to facilitatecommunications between the WTRUs 102 a, 102 b, 102 c and traditionalland-line communications devices. In addition, the gateway 148 mayprovide the WTRUs 102 a, 102 b, 102 c with access to the networks 112,which may include other wired or wireless networks that are owned and/oroperated by other service providers.

Although not shown in FIG. 1C, it will be appreciated that the RAN 104may be connected to other ASNs and the core network 106 may be connectedto other core networks. The communication link between the RAN 104 theother ASNs may be defined as an R4 reference point, which may includeprotocols for coordinating the mobility of the WTRUs 102 a, 102 b, 102 cbetween the RAN 104 and the other ASNs. The communication link betweenthe core network 106 and the other core networks may be defined as an R5reference, which may include protocols for facilitating interworkingbetween home core networks and visited core networks.

Other networks 112 may further be connected to an IEEE 802.11 basedwireless local area network (WLAN) 160. The WLAN 160 shown here may bedesigned to implement the inventive features of the present application.The WLAN 160 may include an access router 165. The access router maycontain gateway functionality. The access router 165 may be incommunication with a plurality of access points (APs) 170 a, 170 b. TheAPs 170 a, 170 b may be configured to perform the methods describedbelow. The communication between access router 165 and APs 170 a, 170 bmay be via wired Ethernet (IEEE 802.3 standards), or any type ofwireless communication protocol. AP 170 a is in wireless communicationover an air interface with WTRU 102 d. WTRU 102 may be an IEEE 802.11STA, and may also be configured to perform the methods described herein.

Herein, the terminology “STA” includes but is not limited to a wirelesstransmit/receive unit (WTRU), a user equipment (UE), a mobile station, afixed or mobile subscriber unit, an AP, a pager, a cellular telephone, apersonal digital assistant (PDA), a computer, a mobile Internet device(MID) or any other type of user device capable of operating in awireless environment. When referred to herein, the terminology “AP”includes but is not limited to a base station, a Node-B, a sitecontroller, or any other type of interfacing device capable of operatingin a wireless environment.

The present application addresses a number of limitations with thecurrent MAC frame design. In the IEEE 802.11-2012 standard, the maximumnumber of identifiable MAC frames is limited by the Type field andSubtype field. With a 2-bit Type field and a 4-bit Subtype field, up to22*24=4*16=64 MAC frames may be defined. The current and proposed usageof the available code points of the combined Type field and Subtypefield is as follows: IEEE 802.11-2012: 38 code points used; IEEE802.11ad: 2 additional code points used; IEEE 802.11ac: 2 additionalcode points used; IEEE 802.11ah: 1 additional code point proposed thusfar; IEEE 802.11ai: 1 additional code point proposed thus far. Insummary, there are 44 code points that have been used or proposed in thecombination of Type field and Subtype field. With the continueddevelopment of the IEEE 802.11 standard, the available code points ofType and Subtype fields for new MAC frames are quickly running out.

In addition, there are different demands for adding new frames fordifferent frame types. For example, there is only one available(currently reserved) code point in the Subtype field for Data frame withType=0b10, and there are only two available (currently reserved) codepoints in the Subtype field for Management frames with Type=0b00.

It should also be pointed out that there currently is one mechanism fordefining new MAC management Action frames, which is to define a newCategory value in the Action frame and/or define a new Public ActionField value for a Public action frame. However, this mechanism onlyapplies to the specific case of Action frames or Public Action frames,and it adds an extra 1 or 2 bytes to the MAC framing overhead.Therefore, the development of efficient mechanisms to support MACframing extensibility in IEEE 802.11-based WLAN systems is needed.

In the IEEE 802.11-2012 standard, the MAC header is designed to be asgeneric as possible for all MAC frames. This is particularly true fordifferent frames within a single type of MAC frame. For example, for MACManagement frames (i.e., Type=0b00), the MAC header format is as shownin FIG. 2. The MAC Management frame format shown in FIG. 2 applies toall of the MAC management frames 200. However, not all of theinformation fields and subfields in the MAC header 202 may be needed forall of the MAC management frames 200, thus resulting in extra MACframing overhead for some MAC frames. For example, for the Beacon frame(Type=0b00 and Subtype=0b1000), the 6-byte destination address 204 maynot be needed, as the Beacon frame is a broadcast frame. In addition,the Beacon frame is transmitted by an AP STA, so the Source Address 206and Basic Service Set Identification (BSSID) 208 are the same, i.e., theAP's 6-byte MAC address. Moreover, the 2-byte Sequence Control (SC)field 210 may not be needed by the Beacon frame. Therefore, 6+6+2=14bytes in the MAC management frame header 202 may not actually be neededfor the Beacon frame, which is 50% of the current 28-byte header. Inaddition, in the 2nd byte of the Frame Control (FC) field 212, i.e., bit8 to 15, only the 1-bit Order indicator 214 applies to the Beacon frame,while the other 7 bits do not apply.

In order to keep backward compatibility of 802.11-based WLAN systems, itmay not be practical to change the MAC format/MAC header design of theexisting MAC frames. However, when addressing MAC frame extensibilityand the introduction of new MAC frames, it may be possible to enhanceencoding efficiency by minimizing MAC framing overhead. This may beparticularly important for WLAN systems with low data rates, e.g., IEEE802.11ah systems with small channel bandwidths. It may also be importantfor new MAC frames that are designed to be transmitted frequently, e.g.,the Fast Initial Link Setup (FILS) Discovery frame in IEEE 802.11aisystems.

It should be also pointed out that a similar issue exists for theInformation Element (IE) encoding format, where the available codepoints of the 1-byte Element ID (EID) field are quickly running out,thus resulting in a serious concern for future evolutions of WirelessLANsystems. Note that the 1-byte EID field gives a total 256 code points,i.e., it may be used to identify a maximum of 256 IEs. In the IEE 802.11standards up to and including IEEE 802.11ad, about 164 IEs have beendefined. There are also multiple IEEE 802.11 development projects thatare currently in progress, e.g., IEEE 802.11ah, IEEE 802.11ai, etc. Eachof these in-progress IEEE 802.11 projects is expected to introduce newIEs, for example, about 25 new IEs are introduced in the current IEEE802.11ah specification Draft 0.1, dated May 2013, and about 14 new IEsare introduced in the current 802.11ai specification Draft 1.0, datedAugust 2013. This means approximately 203 IEs have been defined, leavingonly 53 EID code points remaining. Also, note that the IE format isimportant to IEEE 802.11 MAC management frames, as it is the fundamentalmechanism for encoding variable-size information items and optionalinformation items. It is important to address the extensibility issue ofthe IEs.

The following four solutions address the above identified issues of MACframe extensibility, MAC header inefficiency, and IE extensibility.First, a multi-level extension scheme for MAC frame designs supports theintroduction of new MAC frames as IEEE 802.11-based WLAN technologyevolves. Second, an inventive MAC header structure that consists of twobasic subheaders, a Generic MAC Subheader (GMSH) and a Frame-SpecificMAC Subheader, minimizes the MAC framing overhead by allowing customizedMAC headers. Third, a new addressing scheme in a Class-3 MAC Data frameuses a combination of a BSSID, an association identification (AID), anda Direction indicator to uniquely identify the Source STA and theDestination STA. Fourth, a multi-level extension scheme for IEs providesa backwards compatible solution to the IE format extensibility issue.Further details of these embodiments are provided herein.

The introduction of a multi-level Extension scheme in a MAC frame designwould provide flexible extensibility for the MAC frame design and wouldallow legacy STAs to properly identify and skip over the extensionframes. As used herein, the term “legacy STA” refers to a STA that iscompliant with the WLAN specification before the extension frames areintroduced. The basic embodiments of the multi-level extension schemefirst include assigning a combination or combinations of Type value andSubtype value to identify the Extension frame or frames, where the Typevalue and the Subtype value are chosen from the available values, i.e.,those values currently reserved, based on current IEEE 802.11 MACframes. Another level of “type” information is then introduced withinthe Extension frame, called Sub2type, to identify each individual frameunder the same Type/Subtype combination. These frames are calledExtension-2 frames, and may be identified by a triplet: (Type, Subtype,Sub2type). The invention may further comprise recursively assigning oneor multiple Extension-2 frame identifier triplets for a next level ofExtension frames, called Extension-3 frames. Another level of “type”information may be introduced to identify each Extension-3 frame, calledSub3type. An Extension-3 frame identifier may then be a quadruplet:(Type, Subtype, Sub2type, Sub3type). This step may be applied again, asmany times as needed, each time introducing another level of Extensionframes.

Based on the above-described basic embodiments, multiple variants of themulti-level extension MAC frame design may be introduced to the IEEE802.11-based WLAN systems. The following provides three examples. Thefirst employs a General Extension-2 frame using an Extension Frame Typeand an Extension-2 Frame Subtype. The second embodiment employs a FrameType Specific Extension-2 frame with an Extension Frame Type and anExtension-2 Management Frame Subtype, an Extension-2 Control FrameSubtype, or an Extension-2 Data Frame Subtype. The third embodimentemploys a Frame Type Specific Extension-2 frame with a Management FrameType, a Control Frame Type, or a Data Frame Type. Further details aregiven below.

In a first embodiment of the present invention, one Subtype value underthe Extension Frame Type may be reserved as a general Extension-2 FrameSubtype, which provides further extensibility for MAC frame design. Forexample, if the Subtype value indicates an Extension-2 Frame, then anadditional field with “type” information will be present in the MACheader. A General Extension-2 frame may be any type of MAC frame, e.g.,a Management frame, a Control frame, or a Data frame. Table 1 belowshows an example of Subtype value assignments for Extension frames,where the Extension-2 Frame Subtype is assigned for the GeneralExtension-2 frame. The Type and Subtype values shown below are exemplaryand non-limiting.

TABLE 1 General Extension-2 Frame Type Subtype Value Value (b3 (b7 b6b2) Type Description b5 b4) Subtype Description 11 Extension Frame 0000DMG Beacon (defined in IEEE 802.11adError! Reference source not found.)11 Extension Frame 0001 Short Beacon (defined in IEEE 802.11ah) 11Extension Frame 0010 FILS Discovery Frame (IEEE 802.11ai proposal) 11Extension Frame 0011 to Reserved for future Extension 1110 frames 11Extension Frame 1111 Extension-2 Frame

The Extension-2 frame may use another level of “type” information insidethe Subtype to extend the domain of MAC frame identifications. Such anew level of “Type” may be called Minitype, Subsubtype, Sub2type, etc.Sub2type will be used in the rest of this document to denote the newlevel of type information introduced in the Extension-2 frame.

FIG. 3 shows an example of the basic format of an Extension-2 frame 300.A value in the Type field 302 indicates a general Extension frame, avalue in the Subtype field indicates a general Extension-2 frame, and a6-bit Sub2type field 306 is used to identify each individual Extension-2frame. Some alternative Extension-2 frame basic formats may be designedusing different Subtype values chosen from the currently available setand/or having different sizes, i.e., numbers of bits, for the Sub2typefield 306. An Extension-2 frame may be identified by a triplet, (Type,Subtype, Sub2type). Using the example values shown in Table 1, theExtension-2 frame identifier may be a triplet, (0b11, 0b1111, Sub2type),and the Sub2type field 306 may be a 6-bit field, allowing for a total of64 Extension-2 frames to be identified. The exact coding indicated aboveis purely exemplary and is provided for ease of description, and is notmeant to limit this embodiment in any way.

In order to keep the Extension-2 frame further extendible, one Sub2typevalue may be reserved to identify a next level of extension, i.e.,Extension-3 frames, where another level of “type” information isintroduced, called Sub3type, to identify each individual Extension-3frame. Therefore, an Extension-3 frame may be identified by aquadruplet, (Type, Subtype, Sub2type, Sub3type). For example, ifSub2type=0b111111 is assigned to indicate Extension-3 frames, then anExtension-3 frame identifier is a quadruplet, (0b11, 0b1111, 0b111111,Sub3type). The size of Sub3type may be chosen based on the demand andtendency of the system and technology developments, e.g., 4 bits, 6bits, 8 bits, etc. The above proposed extension scheme may berecursively applied, in order to provide scalable and flexible MAC framedesigns. Again, the embodiment is not limited to the coding indicatedabove, which is purely exemplary.

As shown in FIG. 3, the Extension-2 frame MAC header 308 may consist oftwo basic components, the Frame Control (FC) field 310 and the other MACheader fields 312. The first byte of the FC field 310 of the Extension-2frame 300 may have exactly the same format as the existing MAC frames inWLAN systems, i.e., a 2-bit Protocol Version field 314, a 2-bit Typefield 302, and a 4-bit Subtype field 304. This facilitates Extension-2frame processing. The part of the header comprising the other MAC headerfields 312 may be designed to be generic to all Extension-2 frames orspecific to each individual Extension-2 frame. More detail is providedbelow regarding the processing of the Extension-2 frame 300, and thedesign of the part of the header comprising the other MAC header fields312.

In another embodiment, an indication that the MAC frame is an extensionframe may be included in the PLCP header or PHY preamble. Such anindication may be included using any of the following: one or more bitsin the PHY SIG fields, special code/pattern in the training fields ofthe PLCP header, or special modulation in the PHY SIG fields. Thisadditional PHY layer indication may allow for some additional powersaving for STAs that do not support the extension frames, since suchSTAs may stop decoding the packet after receiving the PLCP header ifthere is a positive indication that the MAC part of the frame is anextension frame. The STA may continue to decode the packet after thePLCP header if there is a negative indication (i.e., the MAC part of theframe is not an extension frame). For STAs that do not support extensionframes, i.e., legacy STAs, a PHY layer indication may speed up thedecoding of the MAC packet due to the early indication in the PLCP thatthe MAC part of the frame is an extension frame.

Similar to any other MAC frame introduced after the first IEEE 802.11standard was published, the Extension-2 frame may be used in a WLANsystem where some STAs may not be able to process the Extension-2 frame,e.g., legacy STAs. Therefore, one fundamental design requirement for theExtension-2 frame is that its introduction not disrupt the operation ofthe legacy STAs. This further requires the Extension-2 frame to beintroduced in such a way that legacy STAs may properly identify it andproceed to the next frame. To achieve this, the following informationitems may be provided to STAs: the identification of the Extension-2frame, the length of the Extension-2 frame, and the location of theExtension-2 frame. The identification of the Extension-2 frame is thecombination of Type value and Subtype value, given in the first byte ofthe FC field 310, which is how STAs currently identify existing MACframes. Therefore, the Extension-2 frame may be identified by bothlegacy STAs and Extension-2 frame capable STAs.

The length information may be provided in the same way as in existingMAC frames, i.e., the length field in the PLCP header, and/or the lengthfield in the MPDU delimiter in the Aggregate MPDU (A-MPDU) format. Notethat this is independent of the introduction of the Extension-2 frameand the design of Extension-2 frame. Similarly, the location informationmay be provided in the same way as existing MAC frames, i.e., in a PPDUor in an A-MPDU.

The Extension-2 frame may be used in WLAN systems that allow coexistenceof legacy STAs and Extension-2 frame capable STAs, with the followinggeneral processing procedure 400, depicted in FIG. 4. Upon receipt ofthe Extension-2 frame (step 402), the STA may validate the receivedframe using a frame checking sequence (FCS) (step 404). The STA may thendecode the first byte of the MAC frame (step 406). If the STA is alegacy STA, it will find that the received frame is an unknown frame bythe Type value and the Subtype value (step 408). It may then end theprocessing of the received frame (step 410), and may choose to sleep forthe rest of received packet as indicated by the length.

Alternatively, if the STA is an Extension-2 frame capable STA, it maydecode the Sub2type subfield to identify the specific Extension-2 frame(step 412). The STA may then decode the remaining MAC header fields(step 414) based on the entire Extension-2 frame identificationinformation triplet, (Type, Subtype, Sub2type). It may process theExtension-2 frame body based on the decoded MAC header information (step416), and finally it may complete the processing of the received frame(step 418).

Note that the frame validation with FCS (step 404) may be the same asthat specified in the current IEEE 802.11 standard, i.e., it may beindependent of the introduction of the Extension-2 frame. The apparatusdepicted in FIGS. 1B and 1C, and specifically the STA 102 d in FIG. 1C,may be configured to process the Extension-2 frame according to thesteps described above and illustrated in FIG. 4.

As an alternative design to the General Extension-2 frame describedabove, a Frame Type Specific Extension-2 frame design may be used thatdefines different Extension-2 frames for different MAC frame types,including MAC Management frames, MAC Control frames, and MAC Dataframes. In this embodiment, under the general Extension Frame Type,Subtype values may be reserved to indicate an Extension-2 Managementframe, and an Extension-2 Control frame, or an Extension-2 Data frame.Table 2 below shows an example of Subtype assignments for the Frame TypeSpecific Extension-2 frames. The Type and Subtype values shown below areagain merely exemplary and are non-limiting.

TABLE 2 Frame Type Specific Extension-2 Frame using Extension Frame TypeType SubType Value Value (b3 (b7 b6 b2) Type Description b5 b4) SubtypeDescription 11 Extension Frame 0000 DMG Beacon (defined in IEEE802.11ad) 11 Extension Frame 0001 Short Beacon (defined in IEEE802.11ah) 11 Extension Frame 0010 FILS Discovery Frame (IEEE 802.11aiproposal) 11 Extension Frame 0011 to Reserved for future Extension 1100frames 11 Extension Frame 1101 Extension-2 Management Frame 11 ExtensionFrame 1110 Extension-2 Control Frame 11 Extension Frame 1111 Extension-2Data Frame

FIG. 5 shows an example of the basic formats of the Frame Type SpecificExtension-2 frames 500, including a Frame Control field for anExtension-2 Management frame 502, an Extension-2 Control frame 506, andan Extension-2 Data frame 510. Note that each Extension-2 frame may havea value in its Subtype field 504, 508, 512 that indicates an Extension-2Management frame, and an Extension-2 Control frame, or an Extension-2Data frame. The values in the Subype fields 504, 508, 512 indicate thepresence of an addition “type” field in each frame, a ManagementSub2type field 514, a Control Sub2type field 516, or a Data Sub2typefield 518. For illustration purpose, FIG. 5 shows that the ControlSub2type field 516 of the Control frame 506 is a 4-bit subfield, whichis different from the Management Sub2type field 514 of the Extension-2Management frame 502 and the Data Sub2type field 518 of the Extension-2Data frame 510. Alternative numbers of bits may be chosen for theSub2type fields of the Control, Management, and Data frames. Inaddition, this embodiment is not limited to the values shown in Table 2.The exact coding indicated above is purely exemplary and is provided forease of description, and is not meant to limit the embodiment in anyway.

Similar to the General Extension-2 frame described above, the Frame TypeSpecific Extension-2 frames 500 may use the multi-level extension schemeto provide further extensions when needed. In addition, with exactly thesame first byte of the FC field as is in existing MAC frames, the FrameType Specific Extension-2 frames may be properly received and processedby Extension-2 frame capable STAs and legacy STAs according to themethod shown in FIG. 4.

As an alternative embodiment, the currently reserved (available) Subtypevalues in the Management Frame Type, Control Frame Type, and Data FrameType may be used to define the Frame Type Specific Extension-2 frames.Table 3 below shows an example of Type and Subtype assignments for theFrame Type Specific Extension-2 frames, where the selected Type/Subtypevalues are currently reserved in the IEEE 802.11 standard. The Type andSubtype values shown below are again merely exemplary and arenon-limiting.

TABLE 3 Frame Type Specific Extension-2 Frame using Management FrameType, Control Frame Type, and Data Frame Type Type SubType Value Value(b3 (b7 b6 b2) Type Description b5 b4) Subtype Description 00 ManagementFrame 1111 Extension-2 Management Frame 01 Control Frame 0101Extension-2 Control Frame 10 Data Frame 1101 Extension-2 Data Frame

Similar to the embodiments described above, another level of “type”information, Sub2type, is introduced in each of the Frame Type SpecificExtension-2 frames, in this case using Type values to indicate aManagement Frame Type, Control Frame Type, and Data Frame Type, andSubtype values to indicate that the frame is an Extension-2 frame. FIG.6 shows an example of the basic formats of the Frame Type SpecificExtension-2 frames 600. For the Extension-2 Management frame 606, avalue in the Type field 602 may indicate a Management frame, and a valuein the Subtype field 604 may indicate an Extension-2 Management frame.Similarly, for the Extension-2 Control frame 612, a value in the Typefield 608 may indicate a Control frame, and a value in the Subtype field610 may indicate an Extension-2 Control frame. Finally, for theExtension-2 Data frame 618, a value in the Type field 614 may indicate aData frame, and a value in the Subtype field 616 may indicate anExtension-2 Data frame. The Sub2type field is defined for eachExtension-2 frame type, as shown in FIG. 6, where the Control Sub2typefield 620 is of 4 bits, different from the Management Sub2type field 618and Data Sub2type field 622. Once again, the number of bits of theSub2type fields 618, 620, 622 is purely exemplary and non-limiting.

Similar to the General Extension-2 frame and Frame Type SpecificExtension-2 frames using a general Extension Frame Type described above,the Frame Type Specific Extension-2 frames using a Management FrameType, Control Frame Type, and Data Frame Type may be properly receivedand processed by Extension-2 frame capable STAs and legacy STAsaccording to the method shown in FIG. 4. While the values shown in Table3 may be used in this embodiment, the embodiment is not limited to thesevalues. The exact coding indicated above is purely exemplary and isprovided for ease of description, and is not meant to limit theembodiment in any way.

Focus is now turned to MAC framing inefficiency. An inventive MAC headerfor IEEE 802.11-based WLAN systems may consist of two subheaders: aGeneric MAC Subheader (GMSH) and a Frame-Specific MAC Subheader(FS-MSH). The GMSH may have the same format in all MAC frames, includinglegacy MAC frames and MAC frames with the inventive MAC header design.The GMSH may contain the information required to distinguish which MACheader format is used, e.g., a legacy MAC header format or the inventiveMAC header format. The FS-MSH may have content and a format designed fora specific MAC frame or a set of MAC frames. The FS-MSH may contain allof the information that is needed to correctly decode and process theMAC frame.

FIG. 7 shows an example of the format of a basic MAC frame 700 with theinventive MAC header design, where the GMSH 702 is 1 byte and has thesame format as the first byte of the FC field of the existing MAC frameheader as specified in the IEEE 802.11 standard. The FS-MSH 704 followsthe GMSH 702, and is described in more detail below.

Note that a MAC frame with the inventive MAC header design may beidentified by STAs through specific values of Type and Subtype in thefirst byte of a MAC frame, for example, the Extension MAC frames asdescribed above. If a STA is capable of processing the MAC frame formatof this embodiment, it may use the information given in the FS-MSH todecode and process the rest of the MAC frame. Otherwise, the STA may usethe length information given in the Physical Layer Convergence Procedure(PLCP) header and/or given in the MPDU delimiter in Aggregate MPDU(A-MPDU) format to bypass the remainder of the current frame and proceedto the next frame. Therefore, the introduction of the MAC format of thisembodiment will not disrupt the operation of legacy STAs that are notcapable of processing the MAC frame with the inventive format. Thisallows the MAC frame format of this embodiment to coexist with thelegacy MAC frame format in WLAN systems, where the legacy STAs canoperate normally, and new STAs (i.e., capable of processing theinventive MAC frame format) can benefit from the encoding efficiencyintroduced by the inventive MAC frame format.

FIG. 8 illustrates the basic structure of the FS-MSH 802 in a basic MACframe 800. The FS-MSH 802 is designed to contain the minimum necessaryinformation for decoding and processing a specific MAC frame or aspecific set of MAC frames, so that MAC framing overhead may beminimized. It generally consists of three components: a Frame-SpecificFrame Control field (FS-FC) 804 that contains the control informationregarding the FS-MSH structure and the MAC frame structure, e.g.,indicating the presence of optional FS-MSH fields in the FS-MSH; one ormore Mandatory FS-MSH fields 806 that must appear in the MAC frame orthe set of MAC frames; and one or more Optional FS-MSH fields 808 thatmay appear in the MAC frame or the set of MAC frames. Further details ofthe FS-MFS design are described below through examples.

In an infrastructure BSS, a Beacon frame is periodically broadcasted bythe AP STA. The IEEE 802.11 Beacon frame has the MAC management frameformat shown in FIG. 2, where some MAC header fields are actually notneeded for the Beacon frame in an infrastructure BSS as pointed outpreviously herein. FIG. 9 shows an example of an Infrastructure BSSBeacon frame 900 with the inventive MAC header design. TheInfrastructure BSS Beacon frame 900 may be encoded as an Extension-2frame with a value in the Type field 904 indicating a general Extensionframe, a value in the Subtype field 906 indicating an Extension-2 frame,and a value in the Sub2type field 908 indicating an Infrastructure BSSBeacon frame. However, other Type, Subtype, and Sub2type values may alsobe used. In FIG. 9, the FS-MSH 902 for the Infrastructure BSS Beaconframe consists of a 1-byte Frame-Specific Frame Control (FS-FC) field910, a 6-byte BSSID field 912, and a 4-byte optional High ThroughputControl (HTC) field 914. Note that the HTC field 914 may include the HTversion/form or the very high throughput (VHT) version/form.

The 1-byte FS-FC field 910 may contain a 6-bit Sub2type field 908 toidentify the MAC frame. It may also contain a 1-bit indicator “HTCPresent” 916 to indicate if the 4-byte HTC field 914 is present in theFS-MSH 902. The HTC Present indicator 916 may be set to one (1) whentransmitted with a value of HT_GF or HT_MF for the FORMAT parameter ofthe TXVECTOR to indicate that the frame contains an HT Control field.FIG. 9 also shows a bit 918 in the FS-FC field 910 that may be reserved.The 6-byte BSSID field 912 may be the AP STA's address. It may also bethe source address of the frame if it is transmitted by the AP STA ofthe infrastructure BSS.

Comparing FIG. 9 to FIG. 2, the MAC framing overhead for theInfrastructure BSS Beacon frame may be significantly reduced by the MACheader design of this embodiment, i.e., from 28 or 32 bytes to 12 or 16bytes depending on HTC presence, due to the removal of several MACheader fields. For example, referring to FIG. 2, the two address fields204 and 206, the Duration/ID field 216, and the Sequence Control field210 may be removed. The MAC framing overhead reduction is particularlyimportant for broadcast frames, as broadcast frames may be transmittedusing the most robust modulation/coding schemes, and therefore are themost expensive in terms of wireless medium occupancy. The MAC framingoverhead reduction is also important for periodic or repeated frames,and for WLAN systems with small channel bandwidth, e.g., IEEE802.11ah-based systems. In these systems the channel bandwidth may be assmall as 1 MHz or 2 MHz, and the data rate may be as low as 100 Kbps. Insuch systems, a MAC frame may occupy up to 20 times more wireless mediumthan in 20 MHz WLAN systems, which makes MAC framing overhead reductionvery important.

The Infrastructure BSS Beacon frame applies to all of theabove-mentioned areas. Based on the IEEE 802.11ah SpecificationFramework Document (SFD), the regular beacon frame still needs to betransmitted, as the IEEE 802.1111ah short beacon may not contain all ofthe information contained in the regular beacon. Considering no legacySTAs in IEEE 802.11ah-based systems, the Infrastructure BSS Beacon frame900 with the MAC header design shown in FIG. 9 may be used in802.11ah-based WLAN systems as an alternative to the existing Beaconframe. These systems would benefit from the 16-byte MAC framing overheadreduction, which translates to 1.28 ms wireless medium occupancyreduction at 100 Kbps. In addition to the MAC framing overheadreduction, the Infrastructure BSS Beacon frame 900 with the MAC headerdesign of this embodiment also allows for optimizations and evenre-designs in the Beacon frame body, as it is a new MAC frame that doesnot need to follow the same frame body design as the existing Beaconframe.

Another type of frame that may benefit from the inventive MAC headerdesign is the Fast Initial Link Setup (FILS) Discovery frame. The FILSDiscovery (FD) frame has been proposed to IEEE 802.11ai, and is designedto provide necessary information transmitted from an AP to STAs for fastinitial link setup. It may be transmitted more frequently than theregular Beacon transmissions, so it may be particularly important tominimize its MAC framing overhead. As shown in FIG. 10, the FD frame1000 may be designed as an Extension frame with a value in the Typefield 1006 indicating an Extension frame, and a value in the Subtypefield 1008 indicating an FD frame, though other Type and Subtype valuesmay also be used. The FD frame design in FIG. 10 gives another exampleof the MAC header design with a Generic MAC Subheader (GMSH) 1002 and aFrame-Specific MAC Subheader (FS-MSH) 1004. The FS-MSH 1004 of the FDframe 1000 may consist of a 2-byte FD Frame-Specific Frame Control(FS-FC) field 1010, a 6-byte BSSID field 1012, and a 4-byte optional HTCfield 1014, where the BSSID and the HTC are the same as in theInfrastructure BSS Beacon frame in FIG. 9. The 2-byte FD FS-FC field1010 may consist of multiple presence indicators, including an HTCpresence indicator 1016, a Capability presence indicator 1018, an AccessNetwork Options (ANO) presence indicator 1020, a Security presenceindicator 1022, an AP Configuration Change Count (AP-CCC) presenceindicator 1024, and an AP's Next Target Beacon Transmission Time (TBTT)(ANT) presence indicator 1026, to indicate whether the frame containscorresponding information items in the FS-MSH 1004 and in the frame body1028. The 2-byte FD FS-FC field 1010 may also comprise control subfieldsto provide the necessary information for decoding and processing theframe, e.g., the SSID Length subfield 1030 and the Neighbor APInformation Control subfield 1032.

Compared to encoding the FD frame in a Management format as shown inFIG. 2, the FD frame 1000 with the inventive MAC header design has asignificant MAC framing overhead reduction, i.e., from 28 or 32 bytes to13 or 17 bytes depending on the HTC presence. In addition, theintroduction of the FD FS-FC field 1010 significantly improves the FDframe body encoding efficiency, compared to using the InformationElement format for variable size information items and optionalinformation items, which is the basic method used in the current IEEE802.11 standard. When using Information Elements, each variable sizeitem or optional item in the FD frame body requires an additional 2bytes for the Element ID field and the Element Length field. In the FDframe example shown in FIG. 10, there are seven content items in the FDframe body that are either variable-size or optional. Therefore, another14 bytes are needed when using the Information Element format instead ofusing the FD FS-FC field 1010.

In addition to the Beacon frame and the FILS Discovery Frame, theClass-3 MAC Data frame may also benefit from the inventive MAC headerdesign. The Class-3 MAC Data frame is defined in the IEEE 802.11-2012standard as a data frame that can only be transported among STAs inState-3 or State-4, i.e., after being authenticated and associated in aninfrastructure BSS or in a mesh BSS (MBSS). In an infrastructure BSS,the association means that the AP STA and the associated non-AP STA haveestablished a known relationship, from which they have certain knowledgeof each other, e.g., MAC address, capabilities, etc., and an AssociationIdentifier (AID) is assigned by the AP STA to identify the associatednon-AP STA. Such knowledge may be used to optimize the MAC frame design.FIG. 11 shows an example of a Class-3 Data frame format with the MACheader design of this embodiment. Note that, in the example shown inFIG. 11, the Class-3 Data frame 1100 with the inventive MAC header isdefined as an Extension frame with values in the Type field 1114 andSubtype field 1116 of the Generic MAC subheader 1112 that indicate aClass-3 Data frame. For example, a value in the Type field 1114 mayindicate a general Extension frame and a value in the Subtype field 1116may indicate a Class-3 Data frame. Alternatively, other available Typeand Subtype values for the Extension frame may be used. In addition, theExtension-2 frame format may be used for the Class-3 MAC Data frame.

For an infrastructure BSS, the current IEEE 802.11-2012 MAC data frame1100 comprises three 6-byte address fields and two 1-bit indicators, ToDS and From DS. Referring to FIG. 11, the three address fields may bereplaced by one 6-byte address field of BSSID 1102 and one 2-byte IDfield of Association ID (AID) 1104. Second, the two 1-bit indicators, ToDS 1112 and From DS 1114, are replaced by a 1-bit Direction indicator1108. The Direction bit is used to indicate the direction of the frameon the “association” in the BSS, either from STA to AP or fro, AP toSTA. In an MBSS, the STA that initiates the association may act as theAP. Between an AP STA and an Associated STA, the combination of theBSSID, AID, and Direction indicator can uniquely identify a pair ofDestination STA and Source STA in an infrastructure BSS, in anydeployment scenario, with or without overlapping BSSs. Therefore, theClass-3 MAC Data frame 1100 with the MAC header design of thisembodiment may be properly received, decoded, and processed using acombination of the BSSID field 1102, the AID field 1104, and theDirection indicator 1108, instead of using a combination of three 6-byteaddress fields and two 1-bit indicators, thus resulting in a 10-byte MACframing overhead reduction.

In addition, for an established association, the AID may be used toidentify the MAC addresses of the associated STAs at both sides of theassociation. Therefore, when a transmitter address (TA) is needed forsending an acknowledgement for a received data frame, the Receiver ofthe data frame may identify the TA based on the AID in the data frame.

The AID as specified in the current IEEE 802.11 standard, 802.11-2012,is a unicast identifier which identifies an established associationbetween two STAs, e.g., between an AP and a non-AP STA in aninfrastructure BSS. The AID in the Class-3 MAC Data frame format may beused for unicast data frames without any changes to the definition ofthe AID concept.

A general processing procedure 1200 for a STA that is capable ofreceiving the Class-3 MAC Data frame of this embodiment is shown in FIG.12. The STA first listens to a beacon and stores the BSSID of thetransmitting AP in a memory component (step 1202). The STA thenassociates with the AP (step 1204), and receives an assigned AID (step1206). The STA may store the AID in a memory component. The STA thenreceives a Class-3 MAC Data frame with the inventive MAC header (step1208). The STA compares the BSSID of the Class-3 MAC Data frame to theBSSID it received upon association (step 1210). If the BSSIDs do notmatch, the STA has determined that it was not the intended recipient ofthe Class-3 MAC Data frame, and may end the processing of the frame(step 1212). If the BSSIDs match, then the STA may compare the AID ofthe Class-3 MAC Data frame to the AID that it received upon association(step 1214). If the AIDs do not match, the STA has determined that itwas not the intended recipient of the Class-3 MAC Data frame, and mayend the processing of the frame (step 1216). If the AIDs match, the STAmay inspect the Direction indicator to determine whether the Class-3 MACData frame has been sent from the AP to the STA (step 1218). If theDirection indicator indicates that the Class-3 MAC Data frame has beensent from the STA to the AP, the STA may end the processing of the dataframe (step 1220). If the Direction field indicates that the Class-3 MACData frame was sent from the AP to the STA, the STA may process theremaining contents of the data frame (step 1222). If the STA wishes tosend an Acknowledgment of the Class-3 MAC Data frame, the STA may usethe BSSID of the received Class-3 MAC Data frame as the Acknowledgementframe's Receiving STA Address.

A general processing procedure is now described for an AP to receive anddecode the Class-3 MAC Data frame of this embodiment. At associationestablishment, when the AP assigns an AID to a STA, the AP may alsorecord the AID and other information about STA in a memory component,e.g., the STA's MAC address, capabilities, QoS requirements, etc. Whenthe AP receives a Class-3 MAC Data frame with the inventive MAC header,the AP may compare the BSSID of the Class-3 MAC Data frame to its ownBSSID. If the BSSIDs do not match, the AP has determined that it was notthe intended recipient of the Class-3 MAC Data frame, and may end theprocessing of the frame. If the BSSIDs match, then the AP may check theAID of the Class-3 MAC Data frame among the AIDs that it has assignedand recorded. If the AID is not in the stored AID list, the AP hasdetermined that it was not the intended recipient of the Class-3 MACData frame, and may end the processing of the frame. If the AID is inthe AP's stored AID list, the AP may inspect the Direction indicator todetermine whether the Class-3 MAC Data frame has been sent from the STAthat has the AID. If the Direction indicator indicates that the Class-3MAC Data frame has been sent from an AP, the AP may end the processingof the data frame. If the Direction bit indicates that the Class-3 MACData frame was sent from the STA, the AP may process the remainingcontents of the data frame. If the AP wishes to send an Acknowledgmentof the Class-3 MAC Data frame to the STA, the AP may use the AID of thereceived Class-3 MAC Data frame to retrieve the STA's addressinformation, which it may use as the Receiving STA Address in theAcknowledgement frame.

The apparatus shown in FIGS. 1B and 1C may be configured to process theClass-3 MAC Data frame as described above and shown in FIG. 12.Specifically, the APs 170 a, 170 b may include a processor, a receiver,a transmitter, and a memory component configured to perform the methodsdescribed above. The STA 102 in FIG. 1C may also include a processor, areceiver, a transmitter, and a memory component configured to performthe methods described herein. The steps described herein are provided asan example. It is not required that all of the steps listed beperformed, nor that they be performed in the order given.

The process described above allows a STA in an infrastructure BSS toreceive and process a Class-3 MAC Data frame using only the BSSID, AID,and Direction fields. The Class-3 MAC Data frame design eliminates threeaddress fields, resulting in a 10-byte MAC framing overhead reduction.This reduction may particularly benefit applications that typically havemany small data packets, as described in more detail below, and may alsobe applied to broadcast and multi-cast Class-3 MAC Data frames.

With the introduction of the inventive Class-3 MAC Data frame, broadcastor multicast (group cast) Class-3 MAC Data frames may continue to betransmitted in the current three-address or four-address Class-3 MACData frame format, or they may be transmitted in the Class-3 MAC Dataframe format shown in FIG. 11, with the following supporting mechanismsregarding the AID's definition and processing. First, the definition ofthe AID may be changed to allow multicast AIDs and broadcast AIDs inaddition to unicast AIDs, where a multicast AID represents a group ofassociated STAs within a BSS, and a broadcast AID is a reserved AID coderepresenting all of the associated STAs within the BSS.

As a second supporting mechanism, the MAC signaling and procedures forforming a STA group, and for adding a STA to or removing a STA from aSTA group, may be defined. For example, the multicast AIDs may be validin the domain of a BSS. In an infrastructure BSS, the AP may manage theAID assignments, including multicast AIDs. The AP may form a STA Groupby itself or upon request by a non-AP STA or STAs. A STA Group may beuniquely identified by a multicast AID within the BSS. A non-AP STA maybecome a member of a STA group when the AP assigns to the STA themulticast AID of the Group. Such a multicast AID assignment may be doneby the AP in an unsolicited manner or upon request by the STA. An AP mayassign a multicast AID to a STA either at the association establishment,e.g., using an Association Response frame, or any time after the STA hasassociated with the AP, e.g., using a MAC management frame.

At the time a multicast AID is assigned to an associated STA, Groupinformation may also be communicated to and stored at the STA, forexample, the information communicated in the address fields of thecurrent three-address or four-address MAC frames. In this way, suchinformation may be retrieved by the STA when needed using the multicastAID presented in a received multicast frame. An associated STA may be amember of zero, one, or multiple STA groups, and thus, the AP may assignit with zero, one or multiple multicast AIDs. The AP may also remove aSTA from a STA Group either by the AP's decision or upon receiving arequest from the STA. Such a removal of a STA from a Group may besignaled by a MAC management message indicating the multicast AID of theGroup, the action (i.e., removal), and any other necessary information.Additionally, the info that a multicast AID may represent may bedefined, for example, mapping the AID to the current three-address orfour-address MAC frame.

As an additional supporting mechanism, a procedure such as that shown inFIG. 13 may be defined for a STA to receive and process a multicastClass-3 MAC Data frame with a multicast AID. The procedure 1300 maybegin with the STA listening to a beacon and storing the BSSID of thetransmitting AP in a memory component (step 1302). The STA may thenassociate with the AP (step 1304). The STA may receive an assignedmulticast AID (step 1306), as well as information about the multicastgroup, and may store the multicast AID and group information in a memorycomponent. The STA may receive a multicast Class-3 MAC Data frame withthe inventive MAC header (step 1308). The STA may compare the BSSID ofthe multicast Class-3 MAC Data frame to the BSSID it received uponassociation (step 1310). If the BSSIDs do not match, the STA hasdetermined that it was not an intended recipient of the multicastClass-3 MAC Data frame, and may end the processing of the frame (step1312). If the BSSIDs match, then the STA may compare the multicast AIDof the Class-3 MAC Data frame to the multicast AID that it received fromthe AP (step 1314). If the multicast AIDs do not match, the STA hasdetermined that it was not an intended recipient of the multicastClass-3 MAC Data frame, and may end the processing of the frame (step1316). If the multicast AIDs match, the STA may inspect the Directionindicator to determine whether the multicast Class-3 MAC Data frame hasbeen sent from the AP to the STA (step 1318). If the Direction indicatorindicates that the multicast Class-3 MAC Data frame has been sent fromthe STA to the AP, the STA may end the processing of the data frame(step 1320). If the Direction field indicates that the multicast Class-3MAC Data frame was sent from the AP to the STA, the STA may process theremaining contents of the data frame (step 1322). When processing thereceived multicast data frame, the STA may also use the multicast AID toretrieve the information about the multicast group that was communicatedand stored at the time the multicast AID was assigned. If the STA wishesto send an Acknowledgment of the multicast Class-3 MAC Data frame, theSTA may use the BSSID of the received data frame as the Acknowledgementframe's Receiving STA Address. The apparatus shown in FIGS. 1B and 1Cmay be configured to process the multicast Class-3 MAC Data frame asdescribed above and shown in FIG. 13.

The MAC framing overhead reduction introduced by the Class-3 MAC Dataframe format of this embodiment may be particularly useful toapplications that typically have many small data packets, e.g.,Machine-to-Machine (M2M) applications with meters/sensors, where atypical data packet size is around tens of bytes. In order to use anIEEE 802.11-based WLAN as the access technology in M2M communicationsystems, it may be important to reduce the MAC framing overhead,particularly in WLAN systems with small channel bandwidth, e.g., in IEEE802.11ah-based WLAN systems.

In addition to the MAC framing overhead reductions introduced by theClass-3 MAC Data frame format shown in FIG. 11, a further overheadreduction may be achieved for the small-size data frame by the followingchanges. First, the 2-byte Sequence Control (SC) 1106 in FIG. 11 may bechanged to a 1-byte SC that contains an 8-bit sequence number, under theconsideration that no fragmentation is needed for a small-size dataframe. Second, the “More Fragment” bit 1118 in the FS-FC field 1110 maybe changed to “reserved.”

In order to resolve the Information Element (IE) extensibility issuedescribed above, a multi-level extension scheme may use a similar basicidea as the multi-level MAC frame extension, i.e., introducing anotherlevel of identifier inside the current IE format for certainpre-determined EIDs. FIG. 14 illustrates an example of the ExtendedInformation Element (EIE) 1400. Referring to FIG. 14, a currentlyavailable EID code point may be reserved for the Extended InformationElement (EIE). This value in the EID field 1402 may indicate thepresence of another ID field, i.e., an Extended Element Identifier(EEID) field 1406. The EEID field 1406 may be introduced after theLength field 1404 to identify Extended Information Elements (EIEs). Thenumber of allowed EIEs may depend on the size of the EEID field 1406,for example, 256 EIEs may be identified using an 8-bit EEID field. Whenusing a 16-bit EEID field, a total of 65,536 EIEs may be identified.Note that the Information body field 1408 for the EIE may be equal tothe value in the Length field 1404 minus the size of EEID field 1406.

The EIE format may be further extended. For example, an EEID may bereserved to introduce another level of extension by using a thirdIdentifier field in the EIE information body called, for example, anExtended-2 EID (E2EID). Therefore, an Extended-2 Information Element(E2IE) may be identified by a triplet, (EID, EEID, E2EID). This step maybe applied again, as many times as needed, each time introducing anotherlevel of Extended Information Elements.

Another alternative method to further extend the EIE format is toreserve multiple EID code points for the purpose of IE extension. Forexample, if N EID code points are reserved to be used in the EID field1402 in FIG. 14, for an 8-bit EEID field 1406, a total number of N times256 (N*256) EIEs may be defined.

The above described Information Element (IE) extension mechanismsprovide flexible extensibility for the IE format design while alsoallowing legacy STAs to properly identify and bypass the EIEs. The term“legacy STAs” here refers to the STAs that are compliant with the WLANspecification before the EIEs are introduced. When a STA receives a MACmanagement frame with an EIE, it may use the EID field value to identifywhether the IE is known or unknown. If the value is unknown, as may bethe case for a legacy STA, it may use the Length field value to properlybypass the IE. If the value is known, the STA may use the EEID field toidentify and process the EID.

Although features and elements are described above in particularcombinations, one of ordinary skill in the art will appreciate that eachfeature or element may be used alone or in any combination with theother features and elements. In addition, the methods described hereinmay be implemented in a computer program, software, or firmwareincorporated in a computer-readable medium for execution by a computeror processor. Examples of computer-readable media include electronicsignals (transmitted over wired or wireless connections) andcomputer-readable storage media. Examples of computer-readable storagemedia include, but are not limited to, a read only memory (ROM), arandom access memory (RAM), a register, cache memory, semiconductormemory devices, magnetic media such as internal hard disks and removabledisks, magneto-optical media, and optical media such as CD-ROM disks,and digital versatile disks (DVDs). A processor in association withsoftware may be used to implement a radio frequency transceiver for usein a WTRU, UE, terminal, base station, RNC, or any host computer.

What is claimed is:
 1. A method for use in an IEEE 802.11 station (STA), comprising: authenticating and associating with an Access Point (AP); receiving a medium access control (MAC) frame which includes a frame control field of the MAC frame, the frame control field of the MAC frame including a first subfield indicating a type of the MAC frame, a second subfield indicating a subtype of the MAC frame and a third subfield indicating a type value of the subtype, wherein for the type of the MAC frame, a value of the second subfield indicates whether or not the third subfield is present in the frame control field of the MAC frame, wherein for the type of the MAC frame, the value of the second subfield has a first value that indicates that the third subfield is present in the frame control field of the MAC frame; and processing the third subfield, based on the first subfield and the second subfield.
 2. The method of claim 1 wherein the first subfield comprises a Type subfield.
 3. The method of claim 1, wherein the second subfield comprises a SubType subfield.
 4. The method of claim 1, wherein the third subfield comprises an Extension-2 subfield.
 5. The method of claim 1, wherein the MAC frame comprises a control frame.
 6. The method of claim 1, further comprising: decoding the third subfield, based on the first subfield, the second subfield, and the third subfield, to determine the type of the subtype.
 7. An IEEE 802.11 station (STA), comprising: a processor comprising circuitry configured to authenticate and associate the IEEE 802.11 STA with an Access Point (AP); and a receiver comprising circuitry configured to receive a medium access control (MAC) frame which includes a frame control field of the MAC frame, the frame control field of the MAC frame including a first subfield indicating a type of the MAC frame, a second subfield indicating a subtype of the MAC frame and a third subfield indicating a type value of the subtype, wherein for the type of the MAC frame, a value of the second subfield indicates whether or not the third subfield is present in the frame control field of the MAC frame, wherein for the type of the MAC frame, a first the value of the second subfield indicates that the third subfield is present in the frame control field of the MAC frame; and wherein the processor further comprises circuitry configured to process the third subfield, based on the first subfield and the second subfield.
 8. The STA of claim 7 wherein first subfield comprises a Type subfield.
 9. The STA of claim 7 wherein the second subfield comprises a SubType subfield.
 10. The STA of claim 7, wherein the third subfield comprises an Extension-2 subfield.
 11. The STA of claim 7 wherein the MAC frame comprises a control frame.
 12. The STA of claim 7 wherein the processor further comprises circuitry configured to decode the third subfield, based on the first subfield, the second subfield, and the third subfield, to determine the type of the subtype. 